engleski

Neuropeptides - substrates of dipeptidyl peptidase III

Dipeptidyl peptidase III (DPP III) is a monozinc peptidase that catalyzes the hydrolytic cleavage of dipeptides sequentially from the N-terminus of peptides which consist of three or more amino acids. It is widely distributed in mammalian tissues and is thought to be involved in the final steps of normal intracellular protein degradation. However, its marked affinity for some bioactive peptides (angiotensin II and III, opioid peptides) suggests more specific functions, such as its role in blood pressure regulation and its involvement in the mammalian pain regulatory system. Cruz-Diaz et al. showed that DPP III degrades angiotensin (1-7) in human renal epithelial cells and suggested a role of DPP III in blood pressure regulation. Colocalization of DPP III in the superficial laminae with enkephalins and endomorphins and the finding that DPP III can degrade these opioid peptides in vitro support the role of DPP III in the endogenous pain regulatory system. We have investigated a number of different (endogenous) neuropeptides as potential substrates and inhibitors of human DPP III. The determined binding affinities and kinetic data in combination with fluorimetric measurements allowed us to distinguish the substrates of human DPP III: Leu- valorphin-Arg and hemorphin-4 from the slow substrates valorphin and β-casomorphin, while four of the total 14 peptides tested did not appear to interact with DPP III as determined by three complementary experimental methods. For the other peptides, the obtained data were mostly consistent with those previously determined.

Dipeptidyl peptidase III ; Neuropeptides ; Substrates ; Inhibitors

This work has been supported by Croatian Science Foundation under the project IP-2018-01-2936.